Using a UPS and Deep Cycle battery(s) to make a reeaaal man's 120 VAC backup

[WA3VJB]

I've heard the efficiency is worse with larger capacity, Tom, without knowing why.  

Can't say I've seen a chart.

APC used to put out white papers discussing the parameters, and efficiency seemed to rank lower for consideration than run time, which I seem to recall was usually spec'd at 50-70% max load.

Just thought of this -- The practical run time estimates didn't explore much about whether a customer might have many or few short duration startup peaks. So, in our setting, the transmit-receive environment might create less of a constant load than "typical."  I bet that's more of an issue than efficiency of the conversion circuit at various prospective load capacities.

The 2200VA that I've got takes FOUR 12 volt gel cells. Trying to remember if it's series @ 48V or series-parallel @ 24V.  I wonder if a 48V supply might improve efficiency at higher load ratings.  

There are various discussions about inter-cell problems as the battery banks get older. One impression I got was that it was better to have fewer but physically larger individual cells to create capacity, rather than a higher number of smaller cells (at higher voltage) for the same capacity.

I just read Bill's generator saga (the empty 5 gallon tank made me grin), and there's a lot of good information among the replies as well.

Also check the survivalist pages in "living off the grid."

Who was the guy in Hawaii on AM who ran his entire house and station on a generator, and otherwise did without electricity.  Used to work him on 10M. I think he passed away between solar cycles.

[W4EWH]

Luckily the longest outage we've had in 18yrs here is 2.5 days, which was last octobers ice storm.  I had a Kerosene heater which kept the house warm and provided hot water for cooking & personal hygene.  We cooked most stuff on the gas grill (electric range is Not So Good) and a coleman stove.  Lights were hurricane lanterns. 

Ed, I'm curious: did the heater come with the house, or did you add it? If the later, how much did it cost when you added it all up? Would you do it again?

We were also out for a couple of days last October (which was when I learned the lessons I alluded to earlier), and I'm preparing for the coming winter, so thanks for your help.

Bill, W1AC

[KF1Z]

Well, there ya go.

Went to Walmart and bought a 114 AH marine deep cycle battery for $109.  (not AGM)   The battery is pretty heavy, maybe 50-60 pounds?

The plastic container was $5.  It has baking soda at the bottom in case of acid leaks, to neutralize.  Notice the vent holes, even though this is a sealed batttery.

The inverter is a $109 300 watt pure sine wave unit and the charger is an automatic $65 "smart" type that shuts off at full charge.

I added a 20A fuse to the battery as well as a disconnect 20A standard light switch.

Tried it out for a few hours with both a light bulb and the SDR radio and all seems to work well.   I don't plan to use it often and should not see a lot of discharges, thus, should last for years.  Maybe add a solar panel charger later.

Total cost: About $290.


So, if this is a 114 AH battery and I am pulling 2A, then it shud last about 57 hours continuous, right?   114/2 = 57.  Consider the pure sine inverter efficiency of about 80% - then let's make that about 45 hours (almost 2 days) at 2A, 10-roger?   The full size computer will take more current, of course, and might last 12 hours at best.


Another use I just thought of...  it could be used to charge any device that uses a 120 VAC wall wart, like cell phone, lap top, etc..

Whenever I need it, just slide it out of the closet, and plug in whatever.  I'll keep the smart trickle charger on it to keep it topped off.
Shud work out FB.


T

Just remember, there is a difference between a Marine STARTING battery, and Marine DEEP CYCLE batt.

But since you don't plan to discharge it on a regular basis, I suppose either one will do you fine.

[K1JJ]

Just remember, there is a difference between a Marine STARTING battery, and Marine DEEP CYCLE batt.

But since you don't plan to discharge it on a regular basis, I suppose either one will do you fine.

Yep, I wondered the same thang when I saw it at Walmart. It was the only battery marked, "deep cycle" and with the price being only $109, I bit.

Can you tell from the picture if it's the less desirable cranking type?  The box said it was for boat trolling, etc., so I figggered it shud handle discharge cycles well.  Maybe not.

I once had a $400 LARGE floor sweeper battery in my truck for a 1500w solid state mobile linear. It lasted about two weeks and went soft. What a waste of money. So I will be careful to limit the discharges.


Paul, OK on the efficiency.  I guess it is best to err on the inefficient side of calculations. I imagine these pure sine wave units are power hogs. After all, just look how fast even a "modified" UPS dies when powering a computer.  So going with a big-ass 2200w unit like yours is a good precaution.

I plan to run this system tonight for eight hours on the medical machine to see what it does. We'll see if the Walmart can stay over 12vdc. It IS a very heavy batt, I must say, for only $109.

Bill, that was quite the story. That Oct storm was really a surprise. We lost power for TEN days. It wasn't really THAT bad cuz of the generator, but got old fast.

T

[W1AEX]

I'm following your battery power project with great interest Tom. I may try to duplicate all of the Vu "Area 51" technological breakthroughs after you elaborate on the results of your finished system.

Funny how that storm last October has affected all of us. Going without power for multiple days in the winter would be disastrous for the plumbing in most homes around here. We were lucky that a sustained period of warm weather followed that storm. I just finished up my generator project here (7500w/9500w peak) to allow us to run the furnace, well pump, refrigerator, freezer, and most of the outlets throughout the house. I figure that the daily usage in my house runs just under 3 bucks a day with CL&P and when I generate my own power it would cost me around 30 bucks in gasoline (@ 4 bucks per gallon) to run the generator 24 hours straight! Not that I would run the generator that way (my plan is 1 hour run and 2 hours off) but it gives some pause for thought about how cheap electrical power actually is.

Rob W1AEX

[K1JJ]

That's an amazing comparison between hambone and commercial power, Rob.  Yep, I always thought electricity was a bargain.  Just think how much energy you'd need to handcrank out enough to power your house....


Here's the customer reviews on my "EverStart MAXX-29 Marine Walmart Battery."  Looks like a fairly good review mixed in with some bummers.  Guess it's a OK deal for the money.

http://reviews.walmart.com/1336/16795213/everstart-maxx-29-marine-battery-reviews/reviews.htm

The key appears to be to use a "smart" charger that will shut off instead of boiling the batt to death.  And don't let the batt get drained to nothing.

T

[KF1Z]

Can you tell from the picture if it's the less desirable cranking type?  The box said it was for boat trolling, etc., so I figggered it shud handle discharge cycles well.  Maybe not.

It says "EverStart".  first glimpse would tell me it's meant as a Marine starting batt....

BUT,
Generally Starting Batts would only list the CCA rating, and not AH.

and Deep Cycle would list AH, and not CCA.

Yours has both printed on the label, AND the box mentions trolling...  so you're
likely ok.

[K3YA]

I've used Wallmart deep cycle batteries in my moterhome for ages.  I'm not sure they all came from the same manufacturer.  I have no complaints about any that I've owned.  Lots of deep discharges and neglect but still provide reasonable life.  Typically after a few years a cell shorts out and I pick up another one.

[W1RKW]

I think the key is how the battery was maintained while on the shelf at the store. Don't know what the turn around time would be on a product like that but if it sits for a long period of time as it self discharges, can't be good. 

[K1JJ]

I think the key is how the battery was maintained while on the shelf at the store. Don't know what the turn around time would be on a product like that but if it sits for a long period of time as it self discharges, can't be good.  

Good point.

Here's a piece of advice I read on the web and actually applied it to the Walmart purchase...

There were about eight of these Maxx-29 marine batts on the shelf.  I grabbed the first one and then remembered to look at the manufacturer's date code and pick the most recent one.  I noticed they all read, "04/2012."    But one in the back row read, "09/2012."   It's not much, but at least I gots one made only a month ago - pretty recently.  Why should I pay the same price for one that was almost 6 months older and probably sat dormant without a boost charge?


T

[WA3VJB]

The word "trolling" on your battery Tom clinches that it's a deep discharge type. Ya done good.

A starting battery can deliver high current for short bursts as a function of its plate construction. It's bad to fully discharge it.

A deep cycle battery can deliver a long discharge to a lower voltage without damage.  But if you try to draw high current, the plates can overheat on the discharge and warp.

There's a loose-leaf book hanging on the battery shelf at the Wal-Mart near Annapolis where lots of boaters buy the marine types.  It 'splains the differences in good detail.  The deep discharge type, says their own book, can withstand about 85 full discharges before performance starts to degrade.

The ones in our area are made by Johnson Controls, although I saw some Exides among side-terminal automotive batts they were selling.

A disgussion of characteristics is here and other places. Intressant.

http://evbatterymonitoring.com/WebHelp/Section_2.htm

You also done good by getting the latest manufacturing date on the shelf. Consumer Reports, in its latest issue, said to avoid those that have been sitting for more than 6 months.  They tend to sulfate, a kind of scum that gets on the lead plates. Partially reversible with use.

I once had a Lucas motorcycle battery that sulfated. The local rep questioned whether my charger was any good, but since it was within warranty he replaced it with fresh stock.

[K5WLF]

Tom,

I think you'll be happy with the WallyWorld EverStart batteries. I've been using the combo start/troll batteries for years in my vehicles. They've been starting the V-6 in the Dakota for nine years now. I just put the third one in about a year ago. The radios get left on sometime for a couple days if I forget to turn 'em off. And the batteries don't grumble at all.

One tip for longevity in a deep cycle battery, more so with AGMs, but applicable to all. Don't draw 'em down to where they're completely flat. A good rule of thumb is to only use half of the Amp-hour rating. So, from a fully charged 100 Ah battery, I'll only take 50 Ah before I charge it again. That makes my two 100 Ah AGMs in parallel a functional 100 Ah battery. They're about 8 years old and still working fine. They usually do backup duty at the house charged with a West Mountain Radio Super PwrGate, but they've gone on many exercises where they were charged with PV panels while being used.

ldb

[K1JJ]

One tip for longevity in a deep cycle battery, more so with AGMs, but applicable to all. Don't draw 'em down to where they're completely flat. A good rule of thumb is to only use half of the Amp-hour rating. So, from a fully charged 100 Ah battery, I'll only take 50 Ah before I charge it again. That makes my two 100 Ah AGMs in parallel a functional 100 Ah battery. They're about 8 years old and still working fine. They usually do backup duty at the house charged with a West Mountain Radio Super PwrGate, but they've gone on many exercises where they were charged with PV panels while being used.

Well, looks like the Maxxxx-29 will be FB then.  Tnx for the info.

Larry, OK on the 50% discharge level precaution.   Eight years of use is amazing. We get what we pay for, especially with those AGM batts.  

Question: What is the best way to "know" how much a battery has been discharged?  

I could see if we used a power meter that created an AH record, or had a constant load for a number of hours.  But is there a simpler way like measuring its voltage to get a reasonably accurate indication when 50% discharge has occured? (without doing an acid specific gravity test)  I wonder if, say, a batt eventually dropped from a starting 13.8 to 11.5V under load, could this be a signal to stop and charge it?  

During emergencies, we tend to get sloppy and could easily push a battery too far into discharge.

Update: Whoops, I just clicked on your battery monitoring link Paul. That looks filled with info on my question. It will take some time to digest. Tnx.

T

[WD5JKO]

Question: What is the best way to "know" how much a battery has been discharged?  

  Tom,  An old rule of thumb used when I was in the UPS business 30 years ago was to kill the UPS when the batteries dropped to 1.75V / cell. That would be 10.5V with a 12V battery. The deep cycle lead acid batteries of that day would take that repeatedly without damage. In fact the UPS systems we designed (up to 10 KVA by paralleling 1KVA modules) were rated upon that variable, and automatically shut off.

   The UPS systems of that day were quite crude by today's standards, some examples:

We evaluated a "step sine wave" inverter from a competitor. All them TO-3 transistors on a huge heatsink was impressive. What was neat was the failure mode where the TO-3 cans in a row acted like Gatling gun as the exploding junctions would melt the metal transistor cover, and throw sparks two meters away.

Another inverter was a self commutating SCR unit rated 10KVA. It kept blowing $100 "semiconductor fuses". So what is a "semiconductor fuse"? Seemed to be a 50 cent fuse relabeled and priced 200X. Both popped after the semiconductors they were "supposed" to protect fused.   Anyway after we blew all the fuses, we (not me) bypassed the fuse...I still remember the 1 awg wires twitching, and the thirty series 2V, 100 AH batteries melting down in a "China Syndrome". What a mess!

We came up with a ferroresonant inverter with the first IR power fets (IRF-100) driving two power NPN transistors, making 1KVA modules that could be stacked. Took 1150 watts to make 1000, but that 150 watts loss was always there, typical of a ferroresonant transformer. This is where I learned that ferrresonance has nothing to do with resonance since the inductor in the L-C tank is a saturated reactor. The resulting "quasi-sine wave" was quite good for the day, and tolerated better by loads than today's step inverters that peak at 150 vac, and yet with a narrowed pulse width to provide 115 vac RMS.

Sorry for the rambling, but UPS systems have a colorful history,

Jim
WD5JKO

[K5WLF]

Question: What is the best way to "know" how much a battery has been discharged?  

Tom,

I use a meter similar to this one:

http://www.powerwerx.com/digital-meters/dc-inline-watt-meter-power-analyzer-bare-wire.html

Mine was made by Medusa Research and I think they're paws up now, but "Watts Up", "Doc Wattson" and the folks above all make similar units. And all are for sale at the Powerwerx site.

ldb

[Ed/KB1HYS]

Luckily the longest outage we've had in 18yrs here is 2.5 days, which was last octobers ice storm.  I had a Kerosene heater which kept the house warm and provided hot water for cooking & personal hygene.  We cooked most stuff on the gas grill (electric range is Not So Good) and a coleman stove.  Lights were hurricane lanterns. 

Ed, I'm curious: did the heater come with the house, or did you add it? If the later, how much did it cost when you added it all up? Would you do it again?

We were also out for a couple of days last October (which was when I learned the lessons I alluded to earlier), and I'm preparing for the coming winter, so thanks for your help.

Bill, W1AC

The Kerosene heater I got from my Father-in-law for hauling it off.  It did need about $30 in parts and a few hours work to make it right.  it's actually a large "portable" unit that supposedly doesn't require venting, which was a plus. I did notice a slight kero smell but that was probably due to a tiny leak I later fixed. That stuff does seem to take for ever to evaporate.   My FIL had used it for years in his duplex when my wife was a girl living there.

  It did heat our small 3 bedroom ranch ok, though the furthest room was a bit chilly like low 50's while the rest of the rooms were kept mid to high 60s.  It got hot enough on the top to actually simmer water, so we put the largest pot we had up there and that was our HW "tank".  We simply filled the sinks from that with ladle.  The girls had to have a bath, so we just heated as much water as we could at once and filled the tub.  All this by the light of hurricane lanterns. All very 1850's lifestyle.

This drove the need for short term 'backup' power so we could have a little light, run the hot water heater, and a small fan to push the warm air around the house a bit better. 

3 marine 'deepcycle' batterys, 1.5KW inverter, battery charger.  Probably <$500 all told, since needs are short term based on history, this aught to be fine.  We don't loose power often or for very long (usually, but now I've jinxed that!). this won't run a large appliane alone (startup current being a problem).   I didn't know about stacking the inverters, as that would probably have been a better route instead of trying to find on large one.

All available from the local autoparts store too I might add.

PV panels would be my next Upgrade.  Looking for power vs budget vs size, and have to convince the XYL that we would actually need them up on the roof.

[K1JJ]

I use a meter similar to this one:

http://www.powerwerx.com/digital-meters/dc-inline-watt-meter-power-analyzer-bare-wire.html

Vely, vely nice device, Larry.  I might just order one today.  Didn't dawn on me that these were available - thought I'd need a power meter like on the outside of the house...   Tnx for the tip.


Jim:  OK on 1.75v per cell or 10.5V being the rough 50% point to recharge a batt.  If I don't get one of those power meters, I'll just hook in a pair of simple volt and amp meters and use 10.5V as my guide.

Yep, you had some crazy experiences when UPS was young. Reminds me of the early days when experimenting with big class E rigs.

T

[W1RKW]

Just to expand on my post above. Anyone remember Two Guys department stores? When I was a teen I worked in the automotive department of a Two Guys department store.   We were tasked once a month to charge the batts for about 1 hour a piece.  We also had batts we "built". They came dry and had to add the electrolyte and apply a charge to get them sale-able.  I think that's a thing of the past these days. But we rarely had a battery come back as failed.

[WA3VJB]

Bob the dry charged battery takes me back to early military radio days.

Came across a few Willard Exide ER-40-6 units, brand new, in their sealed foil wrap, with an outer cloth packing, and a sealed bag with a measured bottle of H₂SO₄ alongside it.  

Around Korean War vintage, I think the date code was 1953.  We filled them up 20 years later and I got at least 7 years of use out of them running wall-mounted emergency lights that our local school had thrown out.

What was cool, and I'm looking for a picture, is that the housing was clear plexiglas, so you could see the charging bubbles and the electrolyte level at any time.



Closest I can find are separate cells in an outer housing.  I also had some ER-40-2 that these resemble.  I think the "40" is amp hours, and the final digit is the voltage of the cell or the pack.

[w3kmp]

I installed this in 1999, preparing for Y2K. The batteries are 6v 340ah, 4 ea for 28vdc. The inverters are Trace DR1524 1500W with battery chargers . The two are connected to supply 110/220vac,  needed to be able to run the deep submersible water pump. The original batteries are still doing okay. I had a second set of Trojan 6v 350ah, but they only lasted about 7 years. They were wet when I got them, which as mentioned, you really do not know how long they were sitting. The set in service now were dry when I got them, and cost less than the Trojans. The wind generator is a Bergey 1.5kw, 10' blade diameter. Three phase ac at about 150 to 180 volts with no load. The run from the wind generator is approximately 500'. A three phase transformer supplies about 28volts to the charge controller.

We have had three close lightning strikes in the last three months.  Two TV's, two Directv dvr's, modem/wireless router, the wind generator charger controller and maybe one inverter. The wind generator is okay, and no radio damage. I can't really complain, as this is the first lightning damage to the wind generator system.

Ken
w3kmp
SW PA

[K1JJ]

Pretty nice wind set up, there, Ken.

I've looked into a few 5-10kw systems myself, but always stopped short when I found out the initial investment - but even more importantly, the cost of replacing the batteries, the lifetime of the generator itself and possible weather damage.  It always made the power grid look cheaper. Of course, yours being a smaller 1500 watt  emergency system, that is a big consideration too.  How do your system expenses calculate out if run continuously?  



**  TEST UPDATE **

Well, I did some test trials on the 114 AH battery inverter system.  Added a current and voltmeter.  Last night I ran the medical machine plugged into the 120VAC inverter. The 13.8 vdc battery draw was  5 amps, 10 amps peak. This is about 96 watts or 7.5AH.

After 9 hours, (68 AH total) the machine continued to run FB and the battery voltage had dropped about 1.8 volts to 12.0 VDC. This is quite acceptable considering our estimate of 10.5vdc for a 50% discharge.

The battery is now recharging at a 1.25A trickle, so should take maybe 54 hours to recharge itself at that slow rate.

I would say the system works as expected and maybe slightly better.

T

[K6IC]

Tom,

Seems that your back-up power system is working well.

(Made a post a few days ago which disappered,  so ...)

A couple of things.  The battery voltage reading is a poor way of determining Sate Of Charge of a battery.  This voltage varies  a large amount depending on any currents into/out of the battery.  Personally,  I'd never,  ever discharge any 12 V lead-acid battery to 10.5 V.  At that point it is DEAD .. errr,  fully discharged.  But this depends upon the discharge current.  Some of the pro level inverters have a Low Voltage Disconnect menu setting.  Normally  the inverter would wait a certain amount of time before shutting off at the set voltage.  Generally the "standard" 10.5-ish LVD on many inverters is really to protect them from excessive currents,  as,  as the DC V in is reduced,  the current increases to maintain the AC output voltage.

The common wisdom about the best value in batteries is the Golf Cart (GC-2)   batteries.  These are 6V @ 225 AH nominal,  and it has been mentioned elsewhere that one can find them at Sam's Club for example for less than $100,  with any core trade in.  I do not go there,  but other similar stores could have a similar value.  These are tough,  real Deep Cycle batts.

RE  TSW inverters vs standby (tare) power.  The large-ish TSW in use here consume 20 watts with no load,  but,  in 24 hours,  the pair burn 1 KWH,  so it does add up.

And something,  believe  VJB Paul mentioned is very true.  Try to run only a single string of batts.  If more capacity is needed,  find larger capacity batts.  This can seem to be more expensive than a number of batts in parallel,  but is it almost impossible to get the batts to share charge/discharge currents well,  and one bad batt can drag the rest of the bank to its knees.  More Pills is not more better.
Just opinions,  GL,  Vic

[w3kmp]

Tom,

In the summer of 1999 the cost for the complete project was about $5000. The system has been trouble free, with the exception of the 1 amp fuse in the charge controller, that has been replaced probably 30 or so times.
This was due to lightning induced transits. With the cost spread over almost 12 years, I feel that at $400 a year it has been acceptable. As far as electrical utility cost savings, no clue. I am amazed that the original set of batteries are still holding up. The generator only has three tapered roller bearings, one for the generator to swivel on, and two for the generator itself. The bearings should be repacked, and the blades inspected. One inverter has gone inop, and the generator charger unit took a good lick from the last lightning surge. The generator 3 phase output is fine. Actually I thought that the generator would have had a lightning strike by now. The terminal strip for the generator feed wires on the step down transformer had actually arced over, but only the 1 amp fuse blew. Batteries are around $300 ea, and the charge controller is unavailable from Beregy. Repair to the one inverter is most likely high. There is a lot of inverters and charge controllers available from China. About three years ago in February we had the power out for 7 days. We have a 5000 watt gas generator, and I would run it during the day, which supplied the house and charged the batteries, and used the batteries and inverters during the night. I had 3 55 gallon drums of gas from 1999, and probably used close to 40 gallons for the week. I am thinking about getting a natural gas conversion for the gas generator. If the SHTF, the natural gas supply would most likely be one of the last things to go. We are surrounded by new Marcellus  gas wells.

The other problem, I am getting too old for climbing towers, and moving 125 pound batteries around.  Had five neck vertebra fused in March, and I am still not back to work. Hopefully, I should be good to go by the end of the month.

I can confirm Vic's comment about not paralleling batteries. I finally just used one bank or the other. The golf cart batteries may be the way to go.

Ken
w3kmp
SW PA

[K1JJ]

Hi Vic,

OK on 10.5vdc being too low.  Good to know.   Looks like I'll be able to get away with a min 12.0 volts based on last night's test.

The golf cart batteries sound interesting. They would have been X2 the AH of my present batt, but in series. Maybe next time.

OK on the big inverters idling at 1KW per day. Guess the smaller choice was correct for this system. Then again, we usually don't keep the inverter idling when not in use.


Ken,

$5K is not too bad for your whole system, especially since yours has lasted 12 years with few minor problems.  Yep, the lightning strikes wud concern me too.  


BTW, I've been seeing a lot of talk about switching over to natural gas cuz it's so cheap. Even the CT governer is talking about it. What some don't realize is price has come down to very low levels over the last year.  It had peaks over 600% higher only two years ago. Those users at the time were hurting bad.

It's like switching over to oil when it was $10/ barrel and freaking out when it rose 1500% later on. Maybe  the best way to play it is have a few fuel combos to draw on when price is best.  

I use coal here every winter and go thru only about  200 gallons of oil per season.  Coal has been slowly creeping up, however, but BTU value still better than oil.

T

[W1RKW]

12v vs. 24v vs. 48v inverters.  What's the advantage/ disadvantage.